Electric drive for sewing machines



3 Sheets-Sheet 1 E. BECKER ELECTRIC DRIVE FOR SEWING MACHINES Feb. 23, 1965 Filed Aug. 14, 1962 Feb. 23, 1965 E. BECKER 3,170,425

ELECTRIC DRIVE FOR SEWING MACHINES Filed Aug. 14, 1962 3 SheetsfSheet 2 Fig. 4

Feb. 23, 1965 E. BECKER 3,170,425

ELECTRIC DRIVE FOR SEWING MACHINES Filed Aug- 14. 1962 5 Sheets-Sheet 3 21 I T+ 1'T-"IH 19 E f l I l l 'j 17 'V l I l 27\ L 1 Fig. 7

` INVENTOR.

ERNST BECKER BY @wmf ATTORNEY.

sewn article to be taken off the machine.

, 3,170,425 l ELECTRC DRTVEFR SEWING MACHINES Emst Becher, Darmstadt, Germany, assigner to Firma Quick-Rotanecker di Co.

Fiied Aug; 14, 1962, Ser. No. 216,9tl4 Claims priority, applicatiorermany, Aug. 16, v1961,

Q 16 Claims. (Cl. i12- 220) same time, the arrangement must ensure that the needle is United States Patent() clear of the fabric, when the sewing machine has thus been turned back. Finally, it isv desired that the reverse rotation and stopping of the machine should be `more rapidly effected than can be done by hand. Moreover, it must also be possible for the machine to be stopped, when required, without reverse rotation. The drive means must, therefore, be so contrived that, optionally, the sewing machine can be brought to a stop Without previous reversal or after previous reversal, the machine stopping in both instances with the l needle in a particular predetermined position which should be always the same.

For solving this problem, the present invention proposes electric drive means for sewing machines, particularly chain stitch sewing machines, comprising a high speed principal drive, a reduced speed drive and a slowspeed drive and electric control means which, by reference to electrical switching pulses impressed upon them, cause the sewing machineto be driven by the several drives in apredetermined sequence, the slow speed drive being eitheral v reverse speed drive or a creep speed forward drive, and the switching sequence being so arrangedthat the reduced speed drive will operate before the main drive" takes over the same angular position throughy aprecisely predetermined angular distance beforestopping.A Theltime ,rep quired for stoppingis appreciably shorter than is possible when turning the machine back by hand. A sewing ma-4 chine drive, -according tothe invention, which includes a Y slow speed reverse drive, operates'by Vdriving the machine at high speed, vwhen the main switch is depressed, whereas A thereduced speed drive becomes efl'ective, lwhen the button` y y is released, causing the machine to slow down to areduced'V speed of 'revolutionandto stop in an axially predetermined i, position,`v wheny the reduced speeddrive is. disengaged.` If

the Vsecpience'of operations includes the ,use of afslow speed reverse drive, then'thisslow speed, drive is actuated,

Vwhen starting and that thereduced4 speed .drivewill opyerate'before the slow when the reduced speed drive cutsout.V 'The 'slow speed y reverse drive' turns back the machine fromy al givenpredetermined initial position: of themainshaft into an exactlyy predetermined angular position. The angle through which the r'nainshaftisturned; in reverse is always the same be` an auxiliary.'relay,`whenthe main relayfis de-energised.

cause the slow speed drive always turns back the mainshaft from the same initial position.A l pe ,l

Since, when starting the machine, the reducedspeed driveis actuated before the high speed drive becomes effec- 3,17%,425 Patented Feb. 23, 1965 ICC tive, it is possible to ensure that even the shortest pulselike depression of the main switch will always cause the machine to be .driven by the reduced speed drive before it is stopped and the stopping position to be the same in lany circumstances. It is thus possible to induce the machine to sew only a single stitch and to stop in the required predetermined angular position by briefly touching and depressing the main switch.

Conveniently, the torque is transmitted toV eachindividual drivethrough -a separate clutch, and it is an advantage if this torque is derived from a single motor, although naturally the-three drives would each be associated with their own driving motor.,

In a preferred form of construction of the invention, the

reduced speed drive and the slow speed drive both operatel on the 'same shaft carrying a worm through which the torque is transmitted to a driving plate frictionally engageable by a clutch plate. Each of the transmissions providing the reduced speed and the slow speed drive is associated with a brake which can be actuated only when both drives are inoperative and which lare both inoperative when only one of the drives is in operation.

In the preferred embodiment of theinvention, the reduced speed drive, 'slow speed drive and principal drive are electromagnetically actuable. control means comprise a circuit for controlling the reduced speed drive and the slow speed drive as well'as a circuit for controlling the magnetically operable clutch plate. A switch is also provided which operates to energise the circuit for the supplementary drives first and then the circuit for the main clutch plate. vWith advantage, the switch contact associated with the supplementary drives is controlled through aV relay equipped with a holding contact for actuating the clutch magnet of drive and the slow speed drive.

y In many instances, it may be desirable to provide twostage single switch control. If this is done, operation ofthe switch by partially depressing the foot pedal may be arranged iirst to start the reducedspeed drive forrforward 'l running of the sewing machine yat a reduced speed (of say 600 r.p.m.). Sewing may be continued at this speed for as long as desired. However, if the foot pedal is then fully depressed, the electromagnetic clutch plate is shifted int0`v tary drives and driven through the reduced speed drive to' revolve for instance-fata speed of 600 r.p.'rn. As soon as` the clutch plate hasaccepted this speed ofrotation, the slipring interrupter deener'gises the relay Acontrolled by the switch, causing'fthe-reduced spe'edzdrive vto disengagethe driving plate.

-In order-to permitV the slow speed drive' to fuliil its in- Y tended function, it isY `advisableto comprise four electrically connected slipringsv in the slip'ring'interrupter,assembly.v `The s'lipring whichserves for yfeeding the/current is a complete ring without a gap,'whereas the three other rings each have an insulating gap, two of them being associated with the holdingV contact of the relay, lwhereas ,thethirdisi connected with a third supplementary contact likewise vassociated with the-relay. "Thissupplementarycontact' energises'the shift magnet of the slow speed-drive through machine to be Aselectably stopped in a position in;which the l needle is either fully raised or fully loweredt,

Conveniently, the electric the reduced speed 3. l Operation of the vselector vswitch may also'determine Whether the sewing machine is to be turned back after stopping. This Will be the case when the' selector switch is in one of its end positions. The sewing machine will vthen stop, when the' main-switch Ahas been released, in a position in which the sewing needle is clearA of the sewn material, permitting the latter to be easily removed from the machine. By placingk the selector switch into its alternative end position, the vreverse drive can be inactivated. The sewing machine will` then stop in the position from which the reverse drive otherwise turns back the mainshaft of the machine.

Instead ofbeing used for driving a chain switch sewing machine which it is desired to bring toa final stop after ithas been turned back, the proposed drive means comprising ,theV lessential features of the invention may also be used ,for driving any' kind of sewing machine required to stop in an extremelyaccurately determined position. In such a case, the slow speed drive is not arranged to be a Vreversing drive but a forward rotating creep speedV drive. Conveniently, a reduction'gearing'rnay then be included in the transmission between the drive formerly constituting theV reverse speed drive and .the motor shaft.

tion of the stopping position of the mainshat of the sew- FIGURE 4 is a sewing machine precision drive,

FIGURES is part of the electric circuit associated withy the slipring interrupter in one'arrangement according ing machine, then suitable arrangements are provided for ensuring that the creep speed drive will always take over from the reduced speed drive as soon 1as the latter is inactivated. To this end, the relay contact which controls Vthe auxiliary relay is permanently connected with the slipring i formerly associated with thefreverse speed `drive.` Vin such an arrangement, the selector switch merely selects the position in which the sewing machine will stop; 1n other words, the selector switch determines whether the rstop` n VVping positionvis with the sewing needle up or down.. v

` In 'order to reduce the current carried by the shprrngs "transistors, for the principal and the auxiliary relay.

. Moreover, in a further development of the invention, the mainswitch may be replaced by a photoelectric vsii/ itching device. YT he drive means can then :be advanv-tageo'usly used for ,the performance of fully automatic i and thusto prolong their lite, it is advisable to substitute kthatis to say, according'toV FIG. l; to the left. couples clutch plate 3 ywith the continuously revolving to FIG. 4,

FIGURE 6 is a modification ofthe electrical circuit in transistorized form, and.

FIG. 7 is-an enlarged sectional'view of onefof the magnetic clutches, speciiically magnetic clutch 19"as seenV from thejright in FIG. l. 1

The motor illustrated in FfG. v1 is intended for driving a chain switch sewing/'machine'. `The .electric motor l drives a iiywheel 2 engageable by a Vclutch-plate which .is connected with a driving pulley'tfor driving the sewingmachine 5; Clutch plate 3 .can be,V axiallyi shifted by means of a magnet 6 built into the bearing box of motor l between clutch plate 3 and driving pulley 4. Y

rEhe winding of magnet fr is fixed. 'Inotherworda it is stationary. The armature S of the magnet iscapable l of limited-axial shift. When magnet 6 is energised, driv-.

ing ulley i and its shaftandclutchplate 3 are shifted towards flywheel Z contrary to thep'ressure of spring 9, This flywheel 2. g Driving pulley 4 will then drive the sewing machineY at'a speed corresponding-with sayV 6G00 stitches per minute. causes clutch plate 3 toengage a bralie disc iti'whichalso serves as a driving plate.` if the brake" disc is stationary, the sewing machine will be stopped immediately.

Brake disc i@ is rotatable and cari be driven by a worm 1,2, and worm wheel il.. The shaft of Worm l2 runs in ball Vbearingsiar and le inthe casing of motor-1.V The free endsfS andl ofthe Worm shaft carry friction discs 17 and'irespectively."y A.The Alatter V,are likewise axially shiftable within lnarrow limits.`. Friction disc 17 is engageableby aV magnetic clutch. 19 'and friction disc 1S by a magnetic V.clutch-riti vdriven by associated drive means@ Magnetic clutch i9 revolves at high speed. VItis driven bya belt.2j.llV from a driving'pulle'y 24 on the shaft 26 of motor. i. lIn analogous manner,y magnetic clutch 20isdriven-by abeltZZ from a driving-puliey 25 on` shaft 26 ,(FIG. 1). -The two transmissions'are adapted vto drive the worm LZthrough. the magnetic clutches in oppositeV directions. Friction ldisc 17 Y can 'be brak'ed.

by a stationary 'magnetic-brake'27, whereasfrictio'n disc Y IS Vcan be'braked bya stationary magnetic brakepZS.

When the required position determined bythe photoelec- -V tric Idevice has been reached, `the sewing Vmachine `is j started up at full speed. Whenthe requir'edlnal position is reached, the supplementary drive kincluding the principal drive are rendered inoperative. t t

Moreover, for automatically. starting Vand y stopping tneV Yslipring may be provided for controlling the. operation'of. v

the cutting device., Finally, the circuit which controls; the clutch platev shift magnet may include vswitch'means 1 FIGURE 3a; shows two-stage'switclli` associated with va yarn tension monitoring means.' V Other features and advantagesof the invention will be described byreference to two embodiments ofthe inven- K' tion illustrated inthe accompanying Vdrawings, in which FIGUREI is a sewing' machinedrive comprising a1 main drive, a reduced speed driveV4 and a slowv speed drive; b FIGURE 2V is the bearing mount of themotor including the clutch, the supplementary drives being-omitted, i

FIGURE 3, is a` circuit diagram-,for controlling .the

motor 'inan'arrangement according toLFIGj. l," Y I aY main switchjin theform of a l, The clutch element@ ymounted fforlrot'ation on the wormshaftgcarrying worm 12 andis driven bynlbelt--ci Friction disc 15.7 is rigidlyconnected to the wormfshaftV lclutchelementt v Y n *"The magnetic clutch contains a" coil, thebeginning of which is taken toa slip` ringand theendof which Ais In-EIG. 7, is shown` an venlargedV sectional viewk ofthe magneticfclutch`19 and ,associated Components; inclu-V .K sive of Wormxf andits wormshaft, ball' bearingl3,ffree end 15 of the Worm shaft, friction ldisc It?, magnetic clutch .19, belt 21,?y stationaryv magnetic vbrake l.'Z.

and cooperates with the;magne-ticrclutch,y 19 to form the connected to Vanotllefr'slip Vrin'gQ The/brushes; used as current supply means-4 slide'over 'thesefvslip" rings, the L brushes being connected to. a currentsupply`` 'The statlonary housing ofthe yassembly containsgstationary magnetie brake 27 and this-brakecontains lanother coil, one

end of whichis connected-to vthe' negativer pole ora Y rectifier- .j while -the other end lis connected togthe winding of theotherfstationary brakefZS and also to1 rest1con- '..tact 33'.;y YWhen thecoilay within-the magnetic clutch-19 isenergizedriction disc 17 iszmoveditothe right Vand is f connected to magnetic clutch 19, .wherefore theA Vworm Vshaft 'and' worm- 172l are driven. When ythe-.coil withiny the stationary magnetic brakeV 27 'is energized, Vfriction l discf17 is move'dtothe left andiis brakedat thestationary Amagnetic brake 27.

f The circuit Vvdiagram'lillustri'atedtiri Sis intended y `for single-switch control. i'ilhenffootv pedal Zijris; de-

If the magnet is de-energised, spring 9 reduced speed drive.

" contactos f tivrely-,be veffected byf a two-stage switch (FIQ. 3a).

the positive poleY and contact 30'. 31 and the winding of magnet 6 are energized. YRelay 31 operates contacts 32, 33 and 34. When contact-33 'is closed, the winding of magnetic clutch 19 of the reduced speed drive is energised. 1

yThe arrangement is such that the combined response times of relay31 and magnetic clutch 19'are shorter than the response time of magnet 6. Thisfensures that depressionof foot pedal 29 causes the winding of magnetic clutch L9 to -be energised before magnet .6 is energised. Even an abrupt closure of the switch of foot pedal 29 followed by immediate release will thus still ensure that the sewing machine needle will stop in the requiredposition. A sudden depression and release of foot pedal 29 may, in some instances, not even shift clutch plate 3 towards the ilywheelZ at all. This will therefore merely be briefly driven through brake disc 10 by the If, in this single-switch control, foot pedal 29 is not lforward direction.

-When foot pedal 29 is released, clutch plate 3 will move into engagement with the forward running brake disc 10, causing the sewing machine to be braked to reduced speed. Relay 31 continues to hold via holding con-v f tact 32 until the holding circuit is broken by` a slip ring interruptorv working in conjunction with condenser 2d'. The capacity of condenser 24 isy suitably chosen to prevent it from supplying relay 31 with power whenl the synchroniser interruptsthe currentj supply so that at the vreduced speed relay 31 will release. The reduced'speed. driveflis thus disconnected at its reduced speed-.of rotation ina preselected 'needle position, forjinstance whenl v Vthe rsewing-needle is down (bottom position). `Resti is responsible for energising the winding of stationary magnetic brake 2 8 in slowspeed drive. T he y sewing machine is thus stopped with the sewing needle in lowered position. f i

Ifit-is'desired to stop the sewing machine in such manner that thev looper is withdrawn from the last formed needle loop, footpedal 29 is depressed and at the same time a selector switch 36 operated. IThis switch isjlocated close alongside the pedal. The selector-switch is so contrived-that when operated it disconnects the holding contact 32 from Va slipringft, `and connects it with a slipring 41;'Selector switch 36'isv incidentally suitably placedto be actuated by-'the operator slightlyshifting his foot to. one Asidewhen depressing `the pedal.' When this is done, the sewing machine'will be automaticallystopped by reference to 'slip ring` 41. The stopping of the. ma-

contact 3810 energisej'shift magneticl clutch 20. in slow speed d rive and simultaneouslyto inactivate the brakes in, the reduced speed drive and slow speedA drive. Thel'slow l ls peed drive will lthereforenow driveQbrake/disc 10i c'ontrary to V"the previous handof rotation, In otherlwords, vthe sewing machineshaft-[will be slowly rotated ,in re-v fverse.v As'soon yasrotation has proceededl through the desired angle in reverse, the brushassociated with a slipfring 42v rideson to :the insulating segment, deenergizingv relay 37 and reenergising the windings of stationary maigvnetic. brakes Z7, 28. The sewing machine will .'now v finally stop in the intended position. Y

` Activation of relay 3ylxand of ymagnet rnay alterna-A Consequently relayimmediately released after having been depressed, then speed drive it will make 600 r.p.m.,whereas when drivenx lf, in this latter case, foot pedal 29 of the sewing ma'- K chine is only half depressed, contact 30 is rst closed,

friction disc 17 is shifted byrnagnetic clutch 19, engaging the drive.v The sewing machine will therefore now be Vdriven forwards through the worm gearing at reduced v' speed, say at 600 rpm. f

- If. foot `pedal 2,9 is then fully depresesd, voltage will be applied to magnet dviaa contact 35, causing clutch lplate .3 to engage the high-speed flywheel 2. The sewing machine will therefore now run at highspeed, ysay 6000 rpm.

The procedure for stopping the machine same as when a single switch control is provided.

The described drive permits the sewing machine to be started at low speed injthe forward direction by half way depression of the foot pedal, the machine running at full speed when the pedal is fully depressed, whereas, by release of the foot'pedal, the machine will bestopped aut'omatically with the needle in a prescribed'position, say fully down lf the selector switch 36 is depressed simultaneously with the depression ofthe foot pedal, the stopping action is as already described, excepting that the.

needle thread loop. The switching times-of the reducedV speed 'drive and ofthe reverse drive are s o short that the entire operation is practically instantaneous. A

YThe motor illustrated in FIGA differs from the motor in FIGS. l to 3 only in that a pulley 39k is driven through intermediate reduction gearingof say l0l'. speed drive thus becomes a creep drive.

chine vwill do :6000 rpm., when driven by the reduced by the creep drive its speed-will be only r.p. m. The object of the creep drive isr merely' to rectify the enfer-in position caused by the reduced speedfdrive. Consequently, slipring 42 is provided with 'a contact segment only in the Vregion of the angulark error due tothe reduced speed drive. Thecreep drive turns the shaft of worm 12 in the same direction as the reduced speed drive.

The ,electrical circuit associated with themotor, according to" FIG. 4,l agrees with the circuit associated with the motorv shown in FIGS. l to 3 excepting that the connecv tion between slipring 43 andcontact 34 is permanent.

'The association of a supplementarycontact'with selector switch 36 may be dispensed with because the sewing ma-A chine isalways finally stopped by the-creep drive. When providing a creep speed drive of-only 60 rpm., the-possible.;deviation of the actual stopping position frfom'the requiredstopping lposition is sm'all enough tobe negliglble.v The sewing machine will in fact stop exactly in the ldesired angular position of the machine shaft. The dei lay vinvolved in having a creep speed is so slight that it is lmore than compensated by the higher sewing speed in the primary stage. The described arrangement isthus the first which 1s capable of reducing-the angular stopping error to within extremely ne limits withoutanyincreaseA in they necessary stopping time.

lln order to reduce the current passing through the. sliprings, the 'circuit may l betransistorised in thev manner` shown 1n FIGL`6. The synchroniser through. which magnetic clutch19 is energi'sed is located in thebase circuit of a vtransistor 43". As soon` as-the brush yrides on to the lnsulated segment of the synchroniser, the windings of magneticclutch-vw are 'defenergi'sed vThrough microswitches L ifi and 45, latteroper-ates the'contacts preis exactly the The slow i i Y The reduction is such `that-,when driven bythe principal drive, the rna-- cofres viously ,operated by relay 3i. "A tuning condenser '46 is Y placed in series with thefwindingV of magnetic'clutch 19V Y across the transiston Together withthi'smagnetic clutch 'flifthe condenser-constitutes an oscillatory circuit.. lWhen .Y the synchroniser rotates at high speed, .tuning condenser,

46,- prevents de-energisation'of magnetic clutch 19. Not until a given speed is reached will the condenser discharge., ,l

5 sufficiently to permit'rnagnetic4 clutch7l9vto be de-enerff gi'sred. Inbotherrwordsthe response (of the synchroniser f 1 at a given speed is determined by Lthe tuning condensery 46. The rnicroswitches 44- and 45 do the workof the relays 3l and 43:7 in the embodiment according to FIGS. l and 4.'- The replacement of the relaysby the transistors throughonly a small distance. When the supplementary drives are braked, therbr'ake ofthe reducedl speed drive is always: activated at the same timeas the brake ofthe reverse running -or creep-speed drive. Sincerthetirne con- Y stants of both brake magnets are-the same, andV thisbraking effortV is Atwice that of a'single brake, the braking effect' is substantially/.greater than in equipment hitherto known, although thetimes requiredare the same in both instances; The accuracyof operation is therefore greatly Vimproved for Vthis reason alone.r

The lmechanical constructionof the arrangementfis the -same as that inthe embodiment according to FIGSnlV kand 4, apart `fromthe transmission ofrto'rque to the creep speed drive.l

electrical circuit associated with the Vmotor isv the same 1 inboth cases, excepting that, :in one instance, the reversingdrive is activatedby reference tothe position o f the l AIn the one case; this ',drivevi's derived direct.. Y ly from the 'motor' shaftand, Vin rthegotherp` through the.. intermediary of a special intermediatetransmission. .The

selector switch, whereas inthe other case,rfthe creep drive l is: alwaysnsed Y ,WhatIclaim'is-'w Y l 4 1`. Drive mechanism fora sewing machine comprising,

a motor including a vdrive 'shaft' having Vopposite output ends, afprirnary high speed drive including'a rotatable flywheel mountedon one of the output ends of the drive shaft of said motor and a rotatable clutch plate engageable by saidiywheel and 'a rotatable'l driving pulley inter- .connected with Ysaid clutch plateV andf a' rotatablejbrake V'disc/'drivingplate, the brake disc/ driving plate andiywheel and clutch plate of said primary high speed drive be-. Ving coaxiaLthe clutchplate .of said primaryn high speed drive being axially'shift'able-between the'iiywheel-Y and bralredisc/ driving lplate Vthereo a K worin lwhe'ei-worm- A. Worm shaft subassernbly for drivingthe brake disc/*drivingV 'v plate of saidprimaryrhigh speeddrive, a'pair-otlauxiliary f drives'including va reduced speed drive andaislowspeed drive, said reduced-speed'drive constitiited byra rotat'ab tween .the magnetic clutch'fand magnetic brake thereof for selectively rotating the `worin shaft-in a certain direc- Y tion of rotationgsaidV slowl speeddriveconstituted by aroy 'td therposinon or selector kswitch position Y j [worm-,worm shaft Il subassernbly and a .rotatable magneticl f;

. clutchrengag'eable with thefriction .discfand driven` a l dr ive'lfr k rnthe opposite output end of theY` drive shaft.V of said -rnotor and-a stationary vmagnetic brake, `the Vmagik fnetic '.clutch,` and' friction discV and magnetici,brake-offA Y l said'reduced speed drive being cnoaxial'gtheA Vfriction disc i of vsaid-redi'l/c'ed.speeddrive Vbeing:.axially shittab1e1bemk f Youtput side ofthe clutch. o

tatable friction discV on. the worm Vshaft of said WormVV Wheeliwor'rn-worrn shaft subassernbly anda rotatable mag` 1 f-netic clutch engage'ablewiththe'frctiondiscV and driven a` windinglot thefshift magnet. Vforthe'clutch vpla *ini aibearing boX `and the*magnet-varniatur'e'.istfastl lfthe'lshift sleeve, the' winding being cylindricalandfernbrac-f. Y'

said slow-speedV drive being-coaXiaL'the `frictionl disc of A' said', slow speeddrive being axially shiftable between j-the-. magneticclutch and` magnetic-,brake thereof Afor,l selec-V Vtively .rotating thel Worm shaft; in ia .direction `of' rotation oppos1te `to .said certain* direction *of rotation, the` Vsaid opposite output end of the drive shaftgof `said motor being a commonipower output to saidV reduced and-slow speed Y drives for driving the wormV shaft successively iny opposite directions'fof.rotation through;thefrespective auxiliary drives of said pair thereof. Y

2. Drive mechanism according tocclaim l Y,havinga single control/switch'for machine starting and stopping.

y z3.,Drive'mechanism accordingto claim 2,` in which the three separate clutches are driven-by said motor:

lifDrive mechanism according toclairn', with the inag- ,Y netic brakes of said reduced speed and slowspeeddrives`A each being koperable onlywhen bothy of said drives are rendered inoperative andbeing jointly releasedY when only one of saidV drives is operational.

' 5. Drive mechanism according to claiin'i, in the clutch;

discsof saidreduced'speed and slow speedV drives each being .electromagnetically operable by electric control means including a main switch for firstV applying a potential. toa circuit` controlling `the drives throughairst switch contactY and then to-a circuit'controlling the drives i through asecond switch Contact. Y s

6. Drive mechanism aceordingto claim5,theiirstswitch K contact being associated with a relay havingfa? holding 1 contactrfor energizing a shift magnetof `said reduced speed.y

drive and a shiftrnagnet of said slowspeed drive.'V

' 7. AA driveaccording toclaim 6.said1relay inV the'controly circuit ofthe auxiliary drvesrot saidpairtherfeof having afl. contactwhichljfilvry establishing-uponrelay energiization Y a connection between the shift-magnet of. said'reducedV Vspeed drive andthe. currentv source .and for establishing "upon'relayde-energizationa connection between ."thevfbraire' magnets Vassociated;V with said-reduced and slowV speed*- drives.y f

8. YDrive :mechanism according to. "claim"7 having "'a':

Yslipring interruptor comprising `four conductively connected sliprings, the lslipring connected with the current [supply l being without a gapjrandthell other slip'rings being-within f gap, two of 'the-.latter being,associatedwith-jrhe ,holding Contact of'said-relay whereas the third precedesa further;

Vswitch Contact',associatedv` withfsaid 4relay v arranged to; n energize the shift` magnet vofthe slo'vvgspeed drive through asupplementary relaywhen saidjrelayisdei ergized.

- 9.."Drive mechanism accordingto"Yclainr8,j ineluding ay selector switch adapted `to'f'connect theholdi'ng Contact of said relay selectablyrwith eithe'rone s lipringor theothe'r.

110.Drivemechanismaccordingtoxclaim9,'said selector` switchV y'comprising v the switching..:element-fior vpermitting A 'the Supplementary. relay iofthrslOW-S'Peed c onnectedwith'and disconnected fromfa {1,1} lDrive mechanismiaccording to cl reduction gear/ing ntergesedmbetw n l2. Drive `mechanism,:according to ingA the lshift sleeve.,

13;*Drive mechanism accordingfto clainl 172 inwnicl'i` j `the jdriving discfis mountedjcna'hub connected with the bearing'boxsand is 'of'inte'gral .construction with the ,worm- Y wheieljsaidfhub 'alsof supporting Ythe shittfsleeve onV the Y-lr4.fDrivei,mechanism'according to clarin l1173, Yin the'rnain switch*isoperablebya foot-pedal such'inanf ner thatjpartialdepressionjot the pedal closes'` 'nelof the u bya drive from the saidopposie outputrend the` drive i shaft of'said motor and a stationary magnetiqbrakethe Vmagnetic clutch and friction disc and magneticbrake4 ofdrive. tol be te 'is iiried switching contacts and :full depression closes the other switching contact. l

15. Drive mechanism according to claim 14, in which the Said relay and the supplementary relay are replaced by transistors.

16. Drive mechanism according to claim 15, in which the slipring interrupter comprises a supplementary slipring -for controlling a yarn cutting device.

References Cited by the Examiner UNITED STATES PATENTS 2,483,017 9/49 McFeaters 74-665 10 8/58 Hale 112-'219 6/ 61 Waninger 74-665 9/61 Schwab 112-219 3/62 Frentzel 112-219 FOREIGN PATENTS 7/57 Great Britain.

10 JORDAN FRANKLIN, Primary Examiner.

DAVID I. WILLIAMOWSKY, Examiner. 

1. DRIVE MECHANISM FOR A SEWING MACHINE COMPRISING, A MOTOR INCLUDING A DRIVE SHAFT HAVING OPPOSITE OUTPUT ENDS, A PRIMARY HIGH SPEED DRIVE INCLUDING A ROTATABLE FLYWHEEL MOUNTED ON ONE OF THE OUTPUTS ENDS OF THE DRIVE SHAFT OF SAID MOTOR AND A ROTATABLE CLUTCH PLATE ENGAGEABLE BY SAID FLYWHEEL AND A ROTATABLE DRIVING PULLEY INTERCONNECTED WITH SAID CLUTCH PLATE AND A ROTATABLE BRAKE DISC/DRIVING PLATE, THE BRAKE DISC/DRIVING PLATE AND FLYWHEEL AND CLUTCH PLATE OF SAID PRIMARY HIGH SPEED DRIVE BEING COAXIAL, THE CLUTCH PLATE OF SAID PRIMARY HIGH SPEED DRIVE BEING AXIALLY SHIFTABLE BETWEEN THE FLYWHEEL AND BRAKE DISC/DRIVING PLATE THEREOF, A WORM WHEEL-WORMWORM SHAFT SUBASSEMBLY FOR DRIVING THE BRAKE DISC/DRIVING PLATE OF SAID PRIMARY HIGH SPEED DRIVE, A PAIR OF AUXILIARY DRIVES INCLUDING A REDUCED SPEED DRIVE AND A SLOW SPEED DRIVE, SAID REDUCED SPEED DRIVE CONSTITUTED BY A ROTATABLE FRICTION DISC ON THE WORM SHAFT OF SAID WORM WHEELWORM-WORM SHAFT SUBASSEMBLY AND A ROTATABLE MAGNETIC CLUTCH ENGAGEABLE WITH THE FRICTION DISC AND DRIVEN BY A DRIVE FROM THE OPPOSITE OUTPUT END OF THE DRIVE SHAFT OF SAID MOTOR AND A STATIONARY MAGNETIC BRAKE, THE MAGNETIC CLUTCH AND FRICTION DISC AND MAGNETIC BRAKE OF SAID REDUCED SPEED DRIVE BEING COAXIAL, THE FRICTION DISC OF SAID REDUCED SPEED DRIVE BEING AXIALLY SHIFTABLE BETWEEN THE MAGNETIC CLUTCH AND MAGNETIC BRAKE THEREOF FOR SELECTIVELY ROTATING THE WORM SHAFT IN A CERTAIN DIRECTION OF ROTATION, SAID SLOW SPEED DRIVE CONSTITUTED BY A ROTATABLE FRICTION DISC ON THE WORM SHAFT OF SAID WORM WHEEL-WORM-WORM SHAFT SUBASSEMBLY AND A ROTATABLE MAGNETIC CLUTCH ENGAGEABLE WITH THE FRICTION DISC AND DRIVEN BY A DRIVE FROM THE SAID OPPOSITE OUTPUT END OF THE DRIVE 